Glucose monitoring sensor and preparation method thereof

Abstract

The invention belongs to the technical field of biosensors, and particularly relates to a glucose monitoring sensor and a preparation method thereof.The glucose monitoring sensor comprises a microneedle array electrode serving as a matrix, the microneedle array electrode is modified with a composite layer of peroxide polypyrrole and tetrathiafulvalene-tetracyano quinolino dimethane, and the composite layer is coated with a composite layer of polypyrrole peroxide and tetrathiafulvalene-tetracyano quinolino dimethane. The preparation method of the sensor comprises the following steps: preparing the microneedle array electrode substrate from the microneedle array electrode base material through two-photon polymerization 3D printing; the micro-needle array electrode substrate is used for preparing a micro-needle array three-electrode by adopting a magnetron sputtering-chlorination process; performing pyrrole monomer polymerization on a working electrode area of the three electrodes of the microneedle array to form a PPyox layer; a TTF-TCNQ composite layer is formed on the PPyox layer; according to the glucose monitoring sensor disclosed by the invention, the sensing performance of the existing CGMS can be improved, the medium loss of the sensor is avoided, the stability is improved, and the detection range is expanded.

Description

Technical Field

[0001] The present invention belongs to the technical field of biosensors, and particularly relates to a glucose monitoring sensor and a preparation method thereof. Background Art

[0002] As the name implies, a glucose sensor is used to detect the glucose concentration in the human body, mainly for patients with type I and type II diabetes. By using continuous glucose monitoring (CGM), the blood glucose level in the body can be viewed in real time through a mobile phone app. For point-of-care testing (POCT) conducted in hospitals, which is the basic form of blood glucose detection, mainly for the detection of glycated hemoglobin / glycated protein / capillary blood glucose. The POCT method belongs to invasive detection, which will cause pain to patients and requires at least multiple detections within a day, which is very inconvenient. The advantage of CGM is that it can detect continuously for 7 - 14 days, reducing the pain and inconvenience of patients' frequent blood sampling.

[0003] The core of an enzyme glucose sensor: glucose oxidase, which essentially generates a charge transfer. A certain concentration of glucose causes a charge transfer through a chemical reaction (generating current) -> calculating the response sensitivity - the lowest detection concentration - the linear range, which are the performance indicators of the sensor. For the final product indicators, there are MARD (mean relative absolute error), calibration, and comfort.

[0004] Glucose sensors can be divided into three generations. The first-generation sensor: requires the participation of oxygen, and finally constructs the relationship between glucose concentration and current by decomposing hydrogen peroxide. Disadvantages: oxygen deficiency problem, high potential causes the decomposition of interfering substances. Solution: control the ratio of glucose + oxygen, and set an interference layer. The second-generation sensor: uses an electron mediator for charge transfer, without the participation of oxygen, and is less affected by interfering substances. Disadvantages: the safety and stability of the mediator. The third-generation sensor: directly decomposes FAD to achieve charge transfer.

[0005] Existing second-generation glucose sensors rely on artificial mediators (such as ferrocene derivatives) to transfer electrons, and there are problems such as easy loss of the mediator, poor stability, and insufficient detection range. Summary of the Invention

[0006] In order to solve the problems in the prior art, the present invention provides a glucose monitoring sensor and a preparation method thereof. By compounding poly (pyrrole - co - oxalate) (PPyox) with tetrathiafulvalene - tetracyanoquinodimethane (TTF - TCNQ) conductive organic salts, the purpose of improving the sensing performance of existing CGMS, preventing the loss of sensor mediators, improving stability, and expanding the detection range is achieved.

[0007] The present invention solves its technical problems by adopting the following technical solutions:

[0008] The object of the present invention is to provide a glucose monitoring sensor, which includes a microneedle array electrode as a matrix, and a composite layer of peroxidized polypyrrole and tetrathiafulvalene-tetracyanoquinodimethane is modified on the microneedle array electrode.

[0009] A preparation method of a glucose monitoring sensor includes the following steps:

[0010] S1: Preparation of the microneedle array electrode matrix: The microneedle array electrode substrate is used to prepare the microneedle array electrode matrix by two-photon polymerization 3D printing;

[0011] S2: Preparation of the microneedle array three-electrode: The microneedle array electrode matrix is used to prepare the microneedle array three-electrode by magnetron sputtering-chlorination process;

[0012] S3: Electrochemical polymerization to prepare the PPyox layer: Pyrrole monomer polymerization is carried out on the working electrode area of the microneedle array three-electrode to form the PPyox layer;

[0013] S4: Preparation of the composite layer: A TTF-TCNQ composite layer is formed on the PPyox layer;

[0014] S5: Enzyme layer modification to obtain the microneedle array electrode sensor: A glucose oxidase mixture solution is coated on the composite layer to obtain the microneedle array electrode sensor.

[0015] Further, the preparation method of the microneedle array electrode matrix includes: designing a conical microneedle model, after hierarchical optimization, setting the layer thickness of 8-12 μm, the laser power of 20-40 mW and the scanning speed of 9000-11000 mm / s, completing the printing of the microneedle array electrode substrate, and then after ultrasonic cleaning with isopropyl alcohol, nitrogen drying and curing in a UV curing box for 20-40 minutes, the microneedle array electrode matrix is formed.

[0016] Further, the microneedle array electrode substrate uses polymethyl methacrylate.

[0017] Further, the preparation method of the microneedle array three-electrode includes: carrying out oxygen plasma cleaning on the microneedle array electrode matrix prepared in S1, then spin-coating photoresist, forming a mask after pre-baking for 8-12 minutes, ultraviolet exposure, post-baking and development; then magnetron sputtering a metal layer, first sputtering a 3-7 nm chromium adhesion layer on the working electrode and counter electrode areas of the microneedle array electrode matrix, and then sputtering a 90-110 nm platinum layer in an argon atmosphere; for the reference electrode area, a 70-90 nm silver layer is sputtered, and finally the glue layer and the covered metal in the unexposed area are dissolved by the stripping solution, only the patterned electrode is retained, and the reference electrode area is soaked in a 0.05-0.15 M FeCl3 solution for 5-15 minutes to obtain the microneedle array three-electrode.

[0018] Further, post-baking is carried out at a constant temperature of 90 - 100 °C for 3 - 7 minutes, and after completion, it is naturally cooled to room temperature; for development, PGMEA developer is used. First, it is left to soak for 2 minutes to dissolve the unexposed area, then ultrasonic-assisted treatment is carried out at 40 kHz and 100 W for 2 minutes, and the total development time is 5 minutes. Subsequently, it is immediately rinsed with isopropanol to terminate the reaction and dried with nitrogen.

[0019] Further, the method for electrochemically polymerizing to prepare the PPyox layer includes: adding 0.4 - 0.8 mol / L pyrrole to a deoxygenated 8 - 12 mmol / L KCl solution, and performing pyrrole monomer polymerization on the working electrode area of the three-electrode of the microneedle array prepared in S2 at +0.5 - 0.9 V (vs. Ag / AgCl), depositing a charge of 700 - 900 mC / cm 2 , to form a polypyrrole film; applying a voltage of +0.5 - 0.9 V overnight in a phosphate buffer solution to form the PPyox layer.

[0020] Further, the method for preparing the composite layer includes: casting 1 - 3 μL of a saturated tetrahydrofuran solution of tetracyanoquinodimethane and 1 - 3 μL of a saturated acetonitrile solution of tetrathiafulvalene on the PPyox layer prepared in S3 in portions, in-situ forming a dendritic crystal structure of TTF-TCNQ, and drying to form a TTF-TCNQ composite layer.

[0021] Further, the method for preparing the microneedle array electrode sensor by enzyme layer modification includes: coating 1 - 3 μL of a PBS mixture containing BSA, glucose oxidase, and glutaraldehyde on the TTF-TCNQ composite layer prepared in S4, and drying to obtain the microneedle array electrode sensor.

[0022] Compared with the prior art, the beneficial technical effects of the present invention are as follows:

[0023] By constructing a third-generation microneedle array electrode sensor for glucose monitoring in interstitial fluid, the present invention realizes wide-range glucose detection (2 - 25 mM for commercially available products, 0.1 - 30 mM for the present invention), and realizes stable monitoring of continuous glucose for 22 days (14 days for commercially available products).

[0024] The above description is only an overview of the technical solution of the present invention. In order to be able to understand the technical means of the present invention more clearly, it can be implemented according to the content of the specification. And in order to make the above content, its purpose, features, and advantages of the present invention more obvious and understandable, the following specifically gives the specific embodiments of the present invention. Brief Description of the Drawings

[0025] Figure 1 It is the standard curve graph of glucose concentration and response current in the test example of the present invention.

[0026] Figure 2This is a stability monitoring result diagram obtained by continuously monitoring the sensor stability test for 22 days in the test example of the present invention. DETAILED DESCRIPTION

[0027] The technical solution of the present invention is further described in detail below in conjunction with specific embodiments. It should be understood that the following embodiments are only exemplary illustrations and explanations of the present invention and should not be construed as limiting the scope of protection of the present invention. All technologies implemented based on the above content of the present invention are included in the scope that the present invention is intended to protect.

[0028] In addition, unless otherwise specified, various raw materials, reagents, instruments and equipment used in the present invention can be purchased from the market or prepared by existing methods.

[0029] Example 1

[0030] A method for preparing a glucose monitoring sensor comprises the following steps:

[0031] 1.3D printing of microneedle array electrode substrate

[0032] A BMF nanoArch S140 two-photon polymerization 3D printer was used with IP-S-grade PMMA photosensitive resin with a resolution of 2 μm as the raw material. A conical microneedle model (base width 300 μm, height 800 μm, tip diameter 20 μm, base spacing 300 μm, base array 5×5) was designed by SolidWorks. After layer optimization, the printing was completed with a layer thickness of 10 μm, a laser power of 30 mW, and a scanning speed of 10,000 mm / s. Subsequently, the microneedle array matrix with a complete structure was formed after ultrasonic cleaning with isopropyl alcohol (5 minutes), nitrogen drying, and curing in a 405 nm wavelength UV curing box for 30 minutes.

[0033] 2. Electrode Functionalization

[0034] ① Preparation of three-electrode system: First, the 3D printed PMMA substrate was cleaned with oxygen plasma (HARRICKPLASMA, 50W, 5 minutes) to enhance adhesion, and then SU-8 photoresist was spin-coated (3000rpm, 30 seconds to form a 10μm film), pre-baked (80℃) for 10 minutes, and UV exposed (365nm, 150mJ / cm 2)、Post-baking and development (the post-baking needs to be carried out at a constant temperature of 95 °C for 5 minutes, and the temperature is raised slowly to avoid thermal stress. After completion, it is naturally cooled to room temperature; for development, a special SU-8 developer (PGMEA) is used. First, it is soaked statically for 2 minutes to dissolve the unexposed area, and then ultrasonically assisted treatment is carried out at 40 kHz and 100 W for 2 minutes. The total development time is 5 minutes. Subsequently, it is immediately rinsed with isopropyl alcohol to terminate the reaction and dried with nitrogen gas) to form a high-resolution mask; then, a metal layer is sputtered using a JCP-350 magnetron sputtering instrument from Zhongke Keyi Co., Ltd. First, a 5 nm chromium adhesion layer (DC 30 W, 2 minutes) is sputtered on the working electrode and counter electrode regions, and then a 100 nm platinum layer (DC 50 W, 15 minutes) is sputtered in an argon atmosphere (vacuum degree 5×10 -4 Pa); for the reference electrode region, an 80 nm silver layer is sputtered, and finally, the SU-8 glue layer and the covered metal in the unexposed area are dissolved by a stripping solution (NMP), and only the patterned electrodes are retained. The reference electrode region is soaked in a 0.1 M FeCl3 solution for 10 minutes to achieve Ag / AgCl conversion, and a micro-needle array three-electrode system is prepared.

[0035] ② Modification of the working electrode

[0036] 1) Electrochemical polymerization: 0.6 mol / L pyrrole (Py) is added to a deoxygenated 10 mmol / L KCl solution, and pyrrole monomer polymerization is carried out on the working electrode region at +0.7 V (vs. Ag / AgCl), depositing a charge of 800 mC / cm 2 , to form a polypyrrole (Ppy) film; a voltage of +0.7 V is applied overnight in a phosphate buffer solution (pH 7.0) to form a PPyox layer.

[0037] 2) Conductive composite layer: 2 μL of a saturated solution of tetracyanoquinodimethane (TCNQ) in tetrahydrofuran (THF) and 2 μL of a saturated solution of tetrathiafulvalene (TTF) in acetonitrile are cast in portions on the PPyox layer to in-situ form a dendritic crystal structure of TTF-TCNQ. After natural drying, a TTF-TCNQ composite layer is formed.

[0038] 3) Enzyme layer modification: 2 μL of a PBS (pH 7.0 - 7.4) mixed solution containing BSA (2%), glucose oxidase (10 mg / mL), and glutaraldehyde (2.5%) is coated, and after natural drying, a micro-needle array electrode sensor is prepared.

[0039] Example 2

[0040] A preparation method of a glucose monitoring sensor, comprising the following steps:

[0041] 1. Preparation of a micro-needle array electrode substrate by 3D printing

[0042] A BMF nanoArch S140 two-photon polymerization 3D printer was used with IP-S-grade PMMA photosensitive resin with a resolution of 2 μm as the raw material. The conical microneedle model (base width 300 μm, height 800 μm, tip diameter 20 μm, base spacing 300 μm, substrate array 5×5) designed by SolidWorks was optimized through layering. The printing was completed with a layer thickness of 8 μm, a laser power of 20 mW, and a scanning speed of 9000 mm / s. Subsequently, the microneedle array matrix with a complete structure was formed after ultrasonic cleaning with isopropyl alcohol (3 minutes), nitrogen drying, and curing in a 405 nm wavelength UV curing box for 20 minutes.

[0043] 2. Electrode Functionalization

[0044] ① Preparation of three-electrode system: First, the 3D printed PMMA substrate was cleaned with oxygen plasma (HARRICKPLASMA, 50W, 5 minutes) to enhance adhesion, and then SU-8 photoresist was spin-coated (2000rpm, 20 seconds to form an 8μm film), pre-baked (70℃) for 8 minutes, and UV exposed (365nm, 150mJ / cm 2 ), post-baking and development (post-baking needs to be kept at 90°C for 3 minutes, and the temperature should be slowly increased to avoid thermal stress, and then naturally cooled to room temperature; development uses SU-8 special developer (PGMEA), first standing and soaking for 2 minutes to dissolve the unexposed area, and then 40kHz, 100W ultrasonic assisted treatment for 2 minutes, the total development time is 5 minutes, and then immediately rinsed with isopropanol to terminate the reaction and dried with nitrogen) to form a high-resolution mask; then the metal layer is sputtered by JCP-350 magnetron sputtering of the working electrode and the counter electrode area, and a 3nm chromium adhesion layer is first sputtered (DC 30W, 2 minutes), and then an argon atmosphere (vacuum degree 4×10 -4 Pa) sputtered a 90nm platinum layer (DC 50W, 15 minutes); the reference electrode area was sputtered a 70nm silver layer, and finally the SU-8 glue layer and the covering metal in the unexposed area were dissolved by a stripping solution (NMP), leaving only the patterned electrode. The reference electrode area was immersed in a 0.05M FeCl3 solution for 5 minutes to achieve Ag / AgCl conversion, and a microneedle array three-electrode system was obtained.

[0045] ② Working electrode modification

[0046] 1) Electrochemical polymerization: 0.4 mol / L pyrrole (Py) was added to the deoxygenated 8 mmol / L KCl solution, and the pyrrole monomer was polymerized at +0.5 V (vs. Ag / AgCl) in the working electrode area, with a deposited charge of 700 mC / cm 2 , forming a polypyrrole (Ppy) film; applying +0.5V voltage overnight in phosphate buffer (pH 7.0) to form a PPyox layer.

[0047] 2) Conductive composite layer: Gradually cast 1 μL of a saturated solution of tetracyanoquinodimethane (TCNQ) in tetrahydrofuran (THF) and 1 μL of a saturated solution of tetrathiafulvalene (TTF) in acetonitrile on the PPyox layer to in-situ form a dendritic crystal structure of TTF-TCNQ. After natural drying, a TTF-TCNQ composite layer is formed.

[0048] 3) Enzyme layer modification: Coat 1 μL of a PBS (pH 7.0 - 7.4) mixed solution containing BSA (2%), glucose oxidase (10 mg / mL), and glutaraldehyde (2.5%). After natural drying, a microneedle array electrode sensor is prepared.

[0049] Example 3

[0050] A method for preparing a glucose monitoring sensor, comprising the following steps:

[0051] 1. Preparation of a microneedle array electrode substrate by 3D printing

[0052] Using a Nanoscribe (BMF) nanoArch S140 two-photon polymerization 3D printer, with IP-S grade PMMA photosensitive resin with a resolution of 2 μm as the raw material, a conical microneedle model designed by SolidWorks (base width 300 μm, height 800 μm, tip diameter 20 μm, base spacing 300 μm, substrate array 5×5) is optimized by layering, and then the layer thickness is set to 12 μm, the laser power is 40 mW, and the scanning speed is 11,000 mm / s to complete the printing. Subsequently, it is ultrasonically cleaned with isopropanol (7 minutes), dried with nitrogen, and cured in a 405 nm wavelength UV curing oven for 40 minutes to form a structurally complete microneedle array substrate.

[0053] 2. Electrode functionalization

[0054] ① Preparation of a three-electrode system: First, perform oxygen plasma cleaning on the 3D-printed PMMA substrate (HARRICK PLASMA, 50 W, 5 minutes) to enhance adhesion. Subsequently, spin-coat SU-8 photoresist (4000 rpm, 40 seconds to form a 12 μm film), pre-bake (90 °C) for 12 minutes, and ultraviolet exposure (365 nm, 150 mJ / cm 2), post-baking and development (post-baking needs to be kept at a constant temperature of 100°C for 7 minutes, and the temperature should be slowly increased to avoid thermal stress. After completion, it should be naturally cooled to room temperature; development uses SU-8 special developer (PGMEA), first standing and soaking for 2 minutes to dissolve the unexposed area, and then 40kHz, 100W ultrasonic assisted treatment for 2 minutes, the total development time is 5 minutes, and then immediately rinsed with isopropanol to terminate the reaction and dried with nitrogen) to form a high-resolution mask; then the metal layer is magnetron sputtered by JCP-350 of Zhongke Instrument, and a 7nm chromium adhesion layer is first sputtered on the working electrode and the counter electrode area (DC 30W, 2 minutes), and then argon atmosphere (vacuum degree 6×10 -4 Pa) sputtered a 110nm platinum layer (DC 50W, 15 minutes); the reference electrode area was sputtered a 90nm silver layer, and finally the SU-8 glue layer and the covering metal in the unexposed area were dissolved by stripping solution (NMP), leaving only the patterned electrode. The reference electrode area was immersed in 0.15M FeCl3 solution for 15 minutes to achieve Ag / AgCl conversion, and a microneedle array three-electrode system was obtained.

[0055] ② Working electrode modification

[0056] 1) Electrochemical polymerization: 0.8 mol / L pyrrole (Py) was added to a deoxygenated 12 mmol / L KCl solution, and the pyrrole monomer was polymerized at +0.9 V (vs. Ag / AgCl) in the working electrode area, with a deposited charge of 900 mC / cm 2 , forming a polypyrrole (Ppy) film; applying a +0.9 V voltage overnight in phosphate buffer (pH 7.0) to form a PPyox layer.

[0057] 2) Conductive composite layer: 3 μL of tetracyanoquinodimethane (TCNQ) saturated solution in tetrahydrofuran (THF) and 3 μL of tetrathiafulvalene (TTF) saturated solution in acetonitrile were cast on the PPyox layer in batches to form a TTF-TCNQ dendritic crystal structure in situ, and a TTF-TCNQ composite layer was formed after natural drying.

[0058] 3) Enzyme layer modification: 3 μL of a mixture of PBS (pH 7.0-7.4) containing BSA (2%), glucose oxidase (10 mg / mL) and glutaraldehyde (2.5%) was coated, and the microneedle array electrode sensor was prepared after natural drying.

[0059] Test example

[0060] The microneedle array electrode sensor prepared in Example 1 was subjected to the following assembly test:

[0061] 1) The three patterned electrodes are connected to silver wires respectively, and the other ends of the silver wires are connected to the interfaces of the electrochemical workstation respectively.

[0062] 2) Testing:

[0063] Testing system: Hydrogels were prepared to mimic the skin; glucose solutions with different concentrations (0.1, 0.5, 1.5, 5, 10, 15, 25, 30 mM) were prepared using artificial interstitial fluid at pH 7.0.

[0064] Determination of the detection range of glucose concentration: Connect the array microneedle system to an electrochemical workstation. Turn on the electrochemical workstation. After the current stabilizes, add equal amounts of glucose solutions of 0.1 mM, 0.5 mM, 1.5 mM, 5 mM, 10 mM, 15 mM, 25 mM, and 30 mM into the hydrogel every 80 s. Obtain the relationship between the change value of the response current and the change in glucose concentration, plot the standard curve between glucose concentration and response current, and determine the detection range of glucose concentration.

[0065] As Figure 1 The results showed that the formula for the standard curve of glucose concentration and response current was: I = 1.8234C - 0.4925, R 2 = 0.9992, where I is the response current (μA) and C is the glucose concentration (mM). The results indicate that the detection range of the array microneedle system obtained in the present invention can be 0.1 - 30 mM.

[0066] Sensor stability test: Connect the array microneedle system to an electrochemical workstation. Turn on the electrochemical workstation. After the current stabilizes, add a 5 mM glucose solution (pH 7.0) prepared with artificial interstitial fluid into the hydrogel and measure three times repeatedly, recording the average current response value. Continuously monitor for 22 days to obtain the stability monitoring results. As Figure 2 The results showed that after 22 days of continuous monitoring, the sensor performance remained basically stable.

[0067] The present invention constructs a third-generation microneedle array electrode sensor for glucose monitoring in interstitial fluid. Poly(methyl methacrylate) (PMMA) is used as the substrate of the microneedle array electrode. The three-electrode system of the microneedle array is formed and prepared by high-precision two-photon polymerization 3D printing and magnetron sputtering-chlorination process. Finally, the working electrode is modified with a functional layer to form a microneedle array electrode sensor. Glucose is oxidized to gluconic acid under the catalysis of glucose oxidase (GOx), and the reduced state of the enzyme (FADH2) directly transfers electrons to the gold electrode through the surface of the TTF-TCNQ crystal, without the need for dissolved oxygen or artificial medium, realizing the third-generation sensing mechanism, improving the sensing performance of the CGMS, avoiding the loss of sensor medium, improving stability, and expanding the detection range.

[0068] The serial numbers of the above embodiments of the present invention are only for description and do not represent the advantages and disadvantages of the embodiments.

[0069] The embodiments of the present invention have been described above in conjunction with the accompanying drawings. However, the present invention is not limited to the above specific embodiments. The above specific embodiments are merely illustrative rather than restrictive. Under the inspiration of the present invention, those of ordinary skill in the art can also make many forms without departing from the spirit of the present invention and the scope protected by the claims. All of these are within the protection scope of the present invention.

Claims

1. A glucose monitoring sensor, characterized in that, It includes a microneedle array electrode as the substrate, and the microneedle array electrode is modified with a composite layer of peroxidized polypyrrole and tetrathiafulvalene-tetracyanoquinodimethane.

2. The preparation method of a glucose monitoring sensor according to claim 1, characterized in that: It includes the following steps: S1: Preparation of the microneedle array electrode substrate: The microneedle array electrode substrate is prepared by two-photon polymerization 3D printing to obtain the microneedle array electrode substrate; S2: Preparation of the microneedle array three-electrode: The microneedle array electrode substrate is used to prepare the microneedle array three-electrode by magnetron sputtering-chlorination process; S3: Electrochemical polymerization to prepare the PPyox layer: Pyrrole monomer polymerization is carried out on the working electrode area of the microneedle array three-electrode to form the PPyox layer; S4: Preparation of the composite layer: A TTF-TCNQ composite layer is formed on the PPyox layer; S5: Enzyme layer modification to obtain the microneedle array electrode sensor: A glucose oxidase mixture solution is coated on the composite layer to obtain the microneedle array electrode sensor.

3. The preparation method of a glucose monitoring sensor according to claim 2, wherein: The preparation method of the microneedle array electrode substrate includes: designing a conical microneedle model, after hierarchical optimization, setting the layer thickness at 8 - 12 μm, the laser power at 20 - 40 mW, and the scanning speed at 9000 - 11000 mm / s, completing the printing of the microneedle array electrode substrate, and then after ultrasonic cleaning with isopropanol, nitrogen drying, and curing in a UV curing box for 20 - 40 minutes, the microneedle array electrode substrate is formed.

4. The preparation method of a glucose monitoring sensor according to claim 3, characterized in that: The microneedle array electrode substrate uses polymethyl methacrylate.

5. The preparation method of a glucose monitoring sensor according to claim 2, wherein: The preparation method of the microneedle array three-electrode includes: performing oxygen plasma cleaning on the microneedle array electrode substrate prepared in S1, then spin-coating photoresist, followed by pre-baking for 8 - 12 minutes, ultraviolet exposure, post-baking, and development to form a mask; then magnetron sputtering a metal layer, first sputtering a 3 - 7 nm chromium adhesion layer on the working electrode and counter electrode areas of the microneedle array electrode substrate, and then sputtering a 90 - 110 nm platinum layer in an argon atmosphere; for the reference electrode area, a 70 - 90 nm silver layer is sputtered, and finally, the glue layer and the covered metal in the unexposed area are dissolved by the stripping solution, only the patterned electrode is retained, and the reference electrode area is soaked in a 0.05 - 0.15 M FeCl3 solution for 5 - 15 minutes to obtain the microneedle array three-electrode.

6. The preparation method of a glucose monitoring sensor according to claim 5, characterized in that: The post-baking is carried out at a constant temperature of 90 - 100 °C for 3 - 7 minutes, and after completion, it is naturally cooled to room temperature; for development, PGMEA developer is used, first statically soaked for 2 minutes to dissolve the unexposed area, then ultrasonically assisted treatment is carried out at 40 kHz and 100 W for 2 minutes, the total development time is 5 minutes, and then immediately rinsed with isopropanol to terminate the reaction and dried with nitrogen.

7. The preparation method of a glucose monitoring sensor according to claim 2, wherein: The method for preparing the PPyox layer by electrochemical polymerization includes: adding 0.4 - 0.8 mol / L pyrrole into a deoxygenated 8 - 12 mmol / L KCl solution, and performing pyrrole monomer polymerization on the working electrode region of the three - electrode of the microneedle array prepared in S2 at +0.5 - 0.9 V (vs. Ag / AgCl) to deposit a charge of 700 - 900 mC / cm 2 , forming a polypyrrole film; applying a voltage of +0.5 - 0.9 V overnight in a phosphate buffer solution to form the PPyox layer.

8. The preparation method of a glucose monitoring sensor according to claim 2, characterized in that: The method for preparing the composite layer includes: casting 1 - 3 μL of a saturated tetrahydrofuran solution of tetracyanoquinodimethane and 1 - 3 μL of a saturated acetonitrile solution of tetrathiafulvalene on the PPyox layer prepared in S3 in batches to in-situ form a TTF-TCNQ dendritic crystal structure, and after drying, a TTF-TCNQ composite layer is formed.

9. The preparation method of a glucose monitoring sensor according to claim 2, characterized in that: The method for enzyme layer modification to obtain the microneedle array electrode sensor includes: coating 1 - 3 μL of a PBS mixture solution containing BSA, glucose oxidase, and glutaraldehyde on the TTF-TCNQ composite layer prepared in S4, and after drying, the microneedle array electrode sensor is obtained.

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